NAME

perlclib - Internal replacements for standard C library functions

DESCRIPTION

One thing Perl porters should note is that perl doesn't tend to use that much of the C standard library internally; you'll see very little use of, for example, the ctype.h functions in there. This is because Perl tends to reimplement or abstract standard library functions, so that we know exactly how they're going to operate.

This is a reference card for people who are familiar with the C library and who want to do things the Perl way; to tell them which functions they ought to use instead of the more normal C functions.

Conventions

In the following tables:

t

is a type.

p

is a pointer.

n

is a number.

s

is a string.

sv, av, hv, etc. represent variables of their respective types.

File Operations

Instead of the stdio.h functions, you should use the Perl abstraction layer. Instead of FILE* types, you need to be handling PerlIO* types. Don't forget that with the new PerlIO layered I/O abstraction FILE* types may not even be available. See also the perlapio documentation for more information about the following functions:

Note also the existence of sv_catpvf and sv_vcatpvfn, combining concatenation with formatting.

Sometimes instead of zeroing the allocated heap by using Newxz() you should consider "poisoning" the data. This means writing a bit pattern into it that should be illegal as pointers (and floating point numbers), and also hopefully surprising enough as integers, so that any code attempting to use the data without forethought will break sooner rather than later. Poisoning can be done using the Poison() macros, which have similar arguments to Zero():

Character Class Tests

There are two types of character class tests that Perl implements: one type deals in chars and are thus not Unicode aware (and hence deprecated unless you know you should use them) and the other type deal in UVs and know about Unicode properties. In the following table, c is a char, and u is a Unicode codepoint.

stdlib.h functions

Notice also the grok_bin, grok_hex, and grok_oct functions in numeric.c for converting strings representing numbers in the respective bases into NVs.

In theory Strtol and Strtoul may not be defined if the machine perl is built on doesn't actually have strtol and strtoul. But as those 2 functions are part of the 1989 ANSI C spec we suspect you'll find them everywhere by now.